Improved voltammetric discrimination of acetaminophen and uric acid in urine using CoO biochar nanocomposite†

Abstract

Overuse of acetaminophen (APAP) has become a severe societal burden in recent years. The rapid and reliable detection of urine APAP concentration can offer certain guidance for better management of APAP usage. This study explored the electrochemical sensing application of a novel electrocatalyst prepared from the biomass of Elaeagnus angustifolia gum. The biomass was first activated by ferric chloride to form a porous biomass carbon material (FBC). Then cobalt oxide (CoC) cracked nanoplate were synthesized by alkali precipitation and calcination and were then hybridized onto the biomass carbon via a simple sonication process. The electrocatalyst of CoO-FBC was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), element mapping, transmission electron microscopy (TEM) and high resolution (HR-TEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), Raman spectroscopy, and nitrogen adsorption/desorption analysis. The CoO-FBC modified glassy carbon electrode (CoO-FBC/GCE) was characterized by various electrochemical methods including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The CoO-FBC/GCE sensor was used to measure APAP in 0.1 M phosphate buffered saline (PBS) with a pH of 7.0, and with two linear sensing ranges from 1 μM to 10 μM and from 10 μM to 100 μM, with a sensitivity of 25.89 μA μM⁻¹ cm⁻² and 10.04 μA μM⁻¹ cm⁻², respectively, and a limit of detection of 0.46 μM. The unavoidable interference in measuring APAP is the inherent uric acid in urine. Uric acid and APAP exhibited adjacent and sometimes unseparable voltammetric peaks. This CoO-FBC/GCE sensor is capable of distinguishing APAP from uric acid and so APAP can be measured in human urine samples with good recoveries. This CoO-FBC/GCE sensor is a promising application for clinical diagnosis and environmental detection.

Keywords: Elaeagnus angustifolia gum; Ferric chloride; Polysaccharide biomass; Cobalt oxide nanoplate; Electrochemical sensing; Analgesic and antipyretic drug.